Hairspray compositions typically contain copolymers as the active ingredient in addition to a carrier. The polymers are typically prepared from a variety of monomers, such as, for example, vinyls, acrylics, acrylamides, unsaturated dicarboxylics and anhydrides. Depending upon the particular monomers employed, the resulting polymers can be anionic, cationic or amphoteric. Typical carders include lower alcohols, i.e., in the C.sub.2 to C.sub.4 carbon range, water and propellants such as alkanes in the C.sub.1 to C.sub.4 carbon range, ethers such as dimethyl ether and gases such as nitrogen and carbon dioxide.
It is not uncommon for the concentration of volatile organic compounds ("VOCs"), e.g., hydrocarbon carders, to comprise a significant amount of the hairspray composition. Usually, the VOC content is about 80 weight percent or more. Many hairsprays are formulated with a VOC content of up to about 95 weight percent. As environmental regulations impose reductions on the amount of VOCs emitted to the atmosphere, hairspray compositions comprising lower levels of VOCs will be required.
Accordingly, in order to comply with changing environmental regulations, polymer compositions suitable for use in hairspray compositions are desired which will allow formulators to provide hairspray compositions comprising a wide range of VOC content. Moreover, it is desired that such hairspray compositions be deliverable from either pump systems or aerosol systems.
Furthermore, when hairspray compositions are formulated with low levels of VOCs, it is desired that such hairsprays, as well as the polymer compositions used therein, have acceptable freeze-thaw stability, i.e., ability to withstand cycles of freezing and thawing. Freeze-thaw stability is an important attribute of such polymer compositions and hairspray compositions because freezing can occur during transportation or storage thereof.
Often, when aqueous-based polymer compositions are subjected to freezing and thawing, a substantial increase in viscosity can occur. Such increases in viscosity can adversely affect the performance of the hairspray, e.g., pumpability, wetting, etc. Freeze-thaw stability can be obtained by introducing antifreeze ingredients, such as, for example, glycols and protective colloids such as hydroxyethyl cellulose and poly(vinylpyrrolidone), or by maintaining the pH at a moderate basicity, e.g., 8.5 or higher. However, introducing such other ingredients into the compositions, or increasing the pH to above about 8.5, may adversely affect other properties, e.g., drying time, curl retention and tackiness, and is therefore undesirable.